FR2746228A1 - SEMICONDUCTOR DEVICE INCLUDING A RING MIXER - Google Patents

Abstract

Semiconductor device for mixing an input signal (IRF) at a first frequency (RF) with an input signal (ILO) from a local oscillator at a second frequency (LO), and for providing a signal of output (OIF) at an intermediate frequency (IF), with rejection of the harmonics of the second frequency (LO) up to a very high order, for example greater than (10), this circuit comprising: - a ring mixer (17) Doubly balanced field-effect transistor (12, 13, 14, 15), having first and second pairs of input terminals (3, 4; 1,2) and having a pair of output terminals (5, 6), - a first and a second coupler (18, 19) respectively phase separator and combiner, for said input signal (IRF) at the first frequency (RF) and the output signal (OIF) at the intermediate frequency (IF), respectively connected to the first pair of input terminals (3, 4) and to the pair of output terminals (5, 6) of the ring mixer (17), and c each consisting of a first and a second subcircuit, respectively (300, 400; 500, 600) identical passive phase shifters formed of localized elements, and mounted symmetrically, so that the respective impedances on the terminals of the first input pair and the terminals of the output pair of the mixer are identical. Converter apparatus or transmitter and / or receiver apparatus including such a device.

Description

"SEMICONDUCTOR DEVICE INCLUDING A RING MIXER"

Description

  A semiconductor device for mixing an input signal at a first RF frequency with an input signal from a local oscillator at a second frequency LO, and for providing an output signal at an intermediate frequency IF, with harmonic rejection of the second LO frequency up to a very high order, for example greater than 10, this circuit comprising a doubly balanced field effect transistor ring mixer. The invention finds its application in the integrated circuit industry for the telecommunications field, and more particularly in the microwave circuit industry.

  monolithically integrated (MMICs).

  A device including a doubly balanced and monolithically integrated mixer having a third order intercept point at a high level is already known from the state of the art by US Patent 5060298 (WAUGH reference of October 22

1991).

  This document describes a microwave mixer which converts an RF frequency of an input signal into an IF intermediate frequency of an output signal by performing the addition between the RF frequency of said input signal and the LO frequency of an input signal. signal

provided by a local oscillator.

  To achieve the mixer itself, four field effect transistors, without drain-source bias, are organized into rings. The transistors are mounted such that a source of one transistor is connected to the source of the adjacent transistor on one side, and the drain of said transistor is connected to the drain of the adjacent transistor on the other side. Grids of

  non-adjacent transistors are coupled in pairs.

  The mixer also includes an impedance transformer circuit (BALUN), a frequency combiner circuit (COMBINER) and a phase separator circuit (PHASE SPLITTER). The impedance transformer circuit comprises at least six distributed stages with field effect transistors, and is applied to the signal from the local oscillator to provide two signals at the LO frequency, in phase opposition, applied to the coupled gates of the transistors. of the ring mixer. It is important to note that this impedance transformer circuit does not have identical impedances on the two output terminals in phase opposition with respect to the ground respectively (FIG. 3 of the document). The combiner circuit has two distributed stages and is applied to the coupled sources of the ring mixer to recombine the output signals at the intermediate IF frequency in phase opposition. It is important to note that to recombine the IF signal and its complementary, this circuit can not have the same impedances on its two input terminals, otherwise the recombined signal would be zero. The phase separator circuit has a dual gate transistor stage and provides, from an RF input signal, two RF signals in phase opposition for applying to the coupled drains of the ring mixer. As with the other circuits applied to the mixer, this phase-separating circuit can not have identical impedances at its output terminals with respect to the mass.

  respectively, otherwise the output signals would be zero.

  This known device is intended to provide an IP3 intercept point of level greater than 30dBm. To reach the fixed goal, this mixing circuit is doubly balanced, that is to say, receives, on the two terminals formed of coupled drains of the transistors, signals in phase opposition, and provides, on the two terminals formed coupled sources transistors, signals in phase opposition; likewise the gates of the transistors coupled in pairs are receiving signals in opposite phase. The signals at the RF and Lo frequencies are in a tight frequency range between 8.5 to 10.5 Ghz to produce a signal at the frequency

  distant intermediate IF of 0.5 to 2 Mhz.

  The device known from the cited document is only interested in the harmonic 3. In general, the skilled person knows that the value of the interception point IP3 depends for the most part on the ring mixer, and that, since field effect transistors are used to make the ring mixer, the value of this interception point is quite high. This value also depends on the transformation ratios of the impedance transformers. A technical problem arises when the input signal at the RF frequency and the output signal at the intermediate frequency IF are in a very narrow frequency range, instead of the signal at the RF frequency and the signal at the frequency of the local oscillator as in the cited document. To produce a signal at the IF intermediate frequency substantially close to the RF frequency of the input signal, the local oscillator signal must then be at a substantially lower LO frequency than that of the RF frequency signal, so that get the mixture of

desired frequencies.

  The person skilled in the art knows that in any mixer system, harmonics are always obtained. When the signal of the local oscillator is at a lower frequency and very different from that of the input and output signals at the frequencies RF and IF which are on the one hand much higher and on the other hand not very different from each other , then, it follows that high-order harmonics, for example, order 10 or 11 harmonics of the signal at the LO frequency of the local oscillator are in the narrow frequency range of the input and output signals. exit

  at the RF and IF frequencies respectively.

  The elimination of harmonics of the LO frequency of the local oscillator, going at least up to the order 10, is therefore a different problem from the problem dealt with by the document cited. This

  problem can only be solved by specific means.

  Another problem that arises today, due to market demand and the state of competition, is that

  only the least energy consuming circuits find takers.

  From this point of view, the device known from the cited document is unfavorable because it is very consumer because the circuits applied to the mixers are active circuits including many stages of transistors. According to the invention these problems are solved by a semiconductor device for mixing an input signal at a first RF frequency with an input signal from a local oscillator at a second frequency L0, and for providing an output signal to an intermediate frequency IF, with harmonic rejection of the second frequency L0 to a very high order, for example greater than 10, which device comprises: a doubly balanced field effect transistor ring mixer having first and second second pairs of input terminals and having a pair of output terminals, first and second couplers respectively separator and phase combiner for said input signal at the first RF frequency and the output signal at the intermediate frequency IF, connected respectively to the first pair of input terminals and to the pair of output terminals of the ring mixer, wherein the first er and the second couplers each consist respectively of a first and a second identical passive phase-shifting sub-circuit formed of localized elements, and mounted symmetrically, so that the respective impedances on the terminals of the first pair of inputs and on

  terminals of the output pair of the mixer are identical.

  An advantage of this device is that the diametrically opposite terminals of the ring mixer see exactly identical impedances over a very wide frequency band, from which it follows that this mixer rejects the harmonics of a very high order, for example of order greater than 10, of the local oscillator signal, when the frequencies of the RF and IF input and output signals are in the narrow frequency range of about 11 to 14.5 Ghz and

  the frequency of the local oscillator is of the order of 1 to 3 Ghz.

  Another advantage of this device lies in a very low consumption of the mixer and couplers, which is particularly favorable at present, this consumption being by

example below 500 mW.

  The diagrammatic FIGS illustrating a device according to the invention are described briefly below: FIG. 1A represents a semiconductor device comprising a ring-shaped transistor with field effect transistors to which a symmetrical coupler and an amplifier for the inputs are applied. , and a symmetrical coupler for the outputs; FIG. 1B represents the device of FIG. 1A with the symmetrical mounting of the couplers; FIG. 2A represents the device of FIG. 1A with, in detail, a symmetrical coupler for the RF frequency input signal; FIG. 2B represents the device of FIG. 1A with, in detail, a symmetrical coupler for the output signal at intermediate frequency IF; FIG. 3 represents an amplifier for the signal at

  the LO frequency of the local oscillator.

  The semiconductor device is described below in

  detail in a preferred embodiment without limitation.

  FIG. 1A shows a semiconductor device for mixing an IRF input signal at a first RF frequency with an input signal ILO at the second LO frequency of a not shown local oscillator, and for providing an OIF output signal to an IF intermediate frequency, with harmonic rejection of the LO frequency of the local oscillator to a high order. This device comprises: a ring mixer 17 with doubly balanced field effect transistors 12,13,14,15, having a first pair of inputs 3,4 for a first signal I (RF) at the first RF frequency and its complementary I (RFB), having a pair of outputs 5.6 for a second signal O (IF) at the intermediate frequency IF and its complement O (IFB), and having a second pair of inputs 1.2 for a third signal I (LO) at the LO frequency of the local oscillator and its complement I (LOB), a first coupler 18 having an external called input terminal 10 for the IRF input signal at the first RF frequency, and a pair of internal called output terminals 3 'and 4' for said first signal and its complement I (RF) and I (RFB) which are connected across the first pair of inputs 3 and 4 of the ring mixer 17, a second coupler 19 having two input terminals called internal 5 'and 6' for the second signal O (IF) and its complement member O (IFB) connected across the pair of outputs 5,6 of the ring mixer 17, and an external called output terminal 8 for said output signal IF1 at the intermediate frequency IF, a third coupler 20 having a terminal d external called input 7 for the input signal ILO from a local oscillator, and a pair of called internal output terminals 1 'and 2' for said third signal I (LO) and its complementary I (LOB) which are connected to the terminals of the second pair of inputs 1

and 2 of the ring mixer 17.

  The input and output signals of the couplers are respectively referenced differently because said couplers can phase shift to a certain extent the signals present on the internal terminals vis-à-vis the signals present on

the external terminals.

  The ring mixer circuit 17 comprises four field effect transistors 12, 13, 14, 15 each having gate, drain and source electrodes, ring-mounted with the drains of the adjacent transistors 12 and 13 on the one hand, and 14 and 15 on the other hand, coupled by two to form the first pair of input terminals 3,4, the gates of the non-adjacent transistors 13 and 15 on the one hand, and 12 and 14 on the other hand, coupled by two crosswise to provide the second pair of input terminals 1,2, and the sources of the adjacent transistors 13 and 14 on the one hand, and 15 and 12 on the other hand, coupled by two to form the

pair of output terminals 5,6.

  This ring mixer circuit further comprises means for continuous polarization gate-drain of the transistors. These polarization means comprise: the application of a bias voltage VG through a resistor RO on the coupled gates of the transistors 12 and 14, the application of a bias voltage VG through a resistor Ri on the coupled gates transistors 13 and 15, the connection of the coupled drains 3 of the transistors 12 and 13 to ground through a resistor R3, the connection of the coupled drains 4 of the transistors 14

  and grounded through a resistor R4.

  Field effect transistors may be of the type

MNIESFET, or better, of the MOSFET type.

  With reference to FIG. 1B, in this semiconductor circuit, the first and second couplers 18, 19 each consist of two identical passive phase-shifting sub-circuits formed of localized elements, referenced respectively 300 and 400 for the first coupler 18, and 500 and 600 for the second coupler 19 and mounted symmetrically, so that for the first and second couplers independently, the impedances on said first and second internal terminals are identical to the ground. As a result, the input terminal 3 and the input terminal 4 of the ring mixer 17 see exactly the same ground impedance, and the output terminal 5 and the mixer output terminal 6 in ring 17 see exactly the same impedance vis-à-vis the mass. The first and second couplers 18, 19 are called symmetric couplers. In the first symmetrical coupler 18, the first sub-circuit 300 and the second sub-circuit 400 each have a first and a second external terminal respectively 33, 39 and 43, 49, and each respectively have a first and a second internal terminal respectively 38, 34 and 48, 44. The two 300,400 sub-circuits are mounted symmetrically. For this purpose, the first external terminal 33 of the first sub-circuit 300 is connected to the external terminal 10 of the corresponding coupler 18, where the input signal IRF is applied to the

  first RF frequency, and the first external terminal 43 of the second sub-frequency

  circuit 400 is connected to a load R11 corresponding to the value of the impedance of the generator of said input signal at the first RF frequency. The second external terminals, respectively 39 and 49, of the first and second subcircuits are cross-coupled to the first internal terminals 48 and 38 respectively of the second and the first subcircuits. These coupling points constitute the internal terminals 3 ', 4' of the corresponding coupler 18. The second internal terminals, respectively 34 and 44 of the first and second sub-circuits

are in the air.

  In the second symmetrical coupler 19, the first sub-circuit 500 and the second sub-circuit 600 each have first and second external terminals 53, 59 and 63, 69 respectively, and each respectively has a first and a second internal terminal respectively. 58, 54 and 68, 64. The two sub-circuits 500, 600 are mounted symmetrically. For this purpose, the first external terminal 53 of the first sub-circuit 500 is connected to the external terminal 8 of the corresponding coupler 19, where the output signal OIF is available, at the intermediate frequency IF, and the first external terminal 63 of the second sub-circuit 600 is connected to a load R9 corresponding to the value of the output impedance. The second external terminals, respectively 59 and 69, of the first and second sub-circuits are cross-coupled to the first internal terminals 68 and 58 respectively of the second and first sub-circuits. These coupling points

  constitute the internal terminals 5 'and 6' of the corresponding coupler 19.

  The second internal terminals, respectively 54 and 64 of the first and the

second subcircuits are in the air.

  The signal present on the second external terminal (39,49) of each subcircuit of the first coupler 18 is 180 degrees out of phase with the signal present on the first internal terminal (38,48), so that the signals present on the internal terminals from the first

  coupler 18 are out of phase by 180.

  The first coupler 18 has a phase separator function since it provides two signals I (RF) and I (RFB) in opposition to

  phase, from the IRF input signal to the RF input frequency.

  The signal present on the second external terminal (59, 69) of each subcircuit of the second coupler 19 is 180 degrees out of phase with the signal present on the first internal terminal (58, 68), the signals O (IF) and O (IFB). ) present on the internal terminals 5 ', 6' of the

  second coupler 19 being out of phase by 1800.

  The second coupler 19 therefore has a combiner function since it provides the output signal OIF at the intermediate frequency

  from the two signals O (IF) and 0 (IFB) in opposite phase.

  Referring to FIGS. 2A and FIG. 2B, each subset

  passive phase shifter circuit 300, 400, 500, 600 comprises: a capacitor 37, 47, 57 67, mounted between the first external terminal 33, 43, 53, 63 and the first internal terminal 38, 48, 58, 68, an inductor 30, 40, 50, 60 mounted between the first external terminal and the second external terminal 39, 49, 59, 69, of a capacitance 35, 45, 55, 65 between the second external terminal and the ground, an inductor 31, 41, 51, 61 between the second external terminal and the second internal terminal 34, 44, 54, 64, of an inductor 32, 42, 52, 62 between the second internal terminal and the first internal terminal with a capacitance 36, 46, 56, 66 between the second internal terminal and the ground. The values of the localized elements constituting the first and the second sub-circuits of the first coupler 18 are respectively exactly identical. The values of the localized elements constituting the first and the second sub-circuits of the second

  coupler 19 are respectively exactly identical.

  With reference to FIG. 3 the third coupler 20 favorably includes a differential amplifier stage and a buffer stage. The differential amplifier stage comprises two field effect transistors 70 and 71 coupled by their common sources to the drain of a transistor 72 mounted as a current source with its source and its gate connected to ground. The drains of the differential transistors are biased by a bias voltage VDD through a resistor, respectively 76 and 77. The connection points of these resistors 76 and 77 at its terminals distributing the bias voltage VDD are coupled by a resistor 74 and a resistor. 75 capacity in parallel. The input signal ILO from the local oscillator is applied to the gate of the first and second differential transistors 70, 71 on an impedance 73 connected to the gate of the first differential transistor 70 and to the ground, the gate of the second transistor differential 71 is also connected to the mass. The gates of the two differential transistors 70, 71 are biased by an arrangement comprising two parallel resistors 78 and 79 whose coupling point is connected to the bias voltage VDD through a resistor 83, and is connected to the

  mass through a resistor 82.

  The buffer stage comprises a first pair of field effect transistors with a low transistor 86 and a high transistor 84 connected in series between the ground and a terminal for the bias voltage VDD, and a second pair of field effect transistors. with a low transistor 87 and a high transistor 85 connected in series between the ground and a terminal for the bias voltage VDD. The drains of the differential transistors 70, 71 are connected directly with the gates of the high transistors 84 and 85 of the first and second pair of transistors of the buffer stage respectively, and are connected directly with the gates of the low transistors 87 and 86. of the second and the first pair of transistors respectively of this buffer stage. The gates of the low transistors are further polarized with respect to the ground at

means of resistors 88 and 89.

  The third signals I (OL) and I (OLB) in phase opposition to the frequency of the local oscillator are available to

  terminals 1 'and 2', at the common points of the high and low transistors.

  With this symmetrical arrangement of the differential stages and buffers, the ring mixer 17 sees identical impedances with respect to the

  mass on its second input terminals 1 and 2.

  By way of example, a semiconductor device as described above has been produced with the following specifications: RF input frequency 13 14.5 GHz IF output frequency 10.95 - 12.75 GHz OL frequency 1.25 - 3, 3 GHz Consumption <500 mW In the first coupler (18) R11 = 50 Q The inductances (30,31,32) = 1nH each The inductances (40,41,42) = 1nH each Capacities (37,47) 0, 1 pF each The capacities (35, 36, 45.46) - 1 pF each In the second coupler (19)

R9 = 50 Q

  The inductances (50,51,52) = lnH each The inductances (60,61,62) = lnH each The capacitances (57,67) 0,1 pF each The capacitances (55,56; 65,66) = - 0 , 1 pF each Continuous insulation capacity has value

about 3 pF.

In the mixer

VG = -1V

Resistances R3 = R4 = 5kP.

  The gate width of the MESFET transistors = 140 μm each. In the third coupler VDD = 8V The gate widths of the transistors of the differential stage = 180 μm. The gate widths of the transistors of the stage

buffer = 70 μm.

  The resistances (76,77) = 260 Q each The resistances (78,79) = 7 kQ each

  Resistances (88.89) = 10 kQ each.

  The semiconductor device described above has been integrated on a substrate of the III-V chemical group, favorably gallium arsenide (GaAs) to form a circuit of the type

  Monolithically Integrated Microwave (MMIC).

  This semiconductor device has been used in a frequency converter apparatus. It can also be favorably used in a transmitter and / or receiver for telecommunication. This semiconductor device can be used for example in satellite reception-transmissions, or for example in radio-relay transmissions which are high-frequency links for telephone, television, etc.

Claims (12)

CLAIMS:   A semiconductor device for mixing an input signal (RFR) at a first frequency (RF) with an input signal (IL0) from a local oscillator at a second frequency (LO), and for providing a signal output (OIF) at an intermediate frequency (IF), with the harmonics of the second frequency (LO) being restored to a very high order, for example greater than 10, this circuit comprising: a ring mixer (17) having doubly balanced field effect (12,13,14,15) having first and second pairs of input terminals (3,4; 1,2) and having a pair of output terminals (5,6); first and second couplers (18,19) respectively separator and phase combiner, for said input signal (IRF) at the first frequency (RF) and the output signal (OIF) at the intermediate frequency (IF), connected respectively to the first pair of input terminals (3,4) and to the pair of output terminals (5,6) of the mixer in ring (17), wherein the first and second couplers (18, 19) each consist of first and second sub-circuits (300,400; 500,60000) identical passive phase shifters consisting of elements located, and mounted symmetrically, so that the respective impedances on the terminals of the first input pair and the terminals of the output pair of the mixer are identical.   2. Device according to claim 1, wherein, the first and second couplers (18,19) each have an external called terminal (10,8) for respectively said input signal (RFR) at the first frequency (RF) and the output signal (OIF) at the intermediate frequency (IF), and a pair of internal called terminals (3 ', 4'; 5 ', 6') for respectively first signals in phase opposition to the frequency of said signal (I (RF), I (RFB)), and second phase-opposite signals (I (IF), I (IFB)) at the frequency of the output signal, and are respectively connected to the first pair of input terminals (3,4) and to the pair of output terminals (5,6) of the ring mixer (17), and wherein in the first and second couplers (18,19) the first and second sub-circuits each have first and second external terminals, and first and second internal terminals, and are symmetrically mounted with the first external terminal (33, 53) of the first subcircuit (300,500) connected to the external terminal (10,8) of the corresponding coupler (18,19), and the first external terminal (43,63) of the second subcircuit (400,600) connected to a load (R11 , R9), and with the second external terminal (39,49; 59,69) of each sub-circuit cross-coupled with the first internal terminal (38,48; 58,68) of the symmetrical sub-circuit, these coupled terminals being respectively connected to the first and the second terminals   internals (3 ', 4', 5 ', 6') of the corresponding coupler (18, 19).   3. Device according to claim 2, in which each passive phase shifting sub-circuit consists of: a capacitance (37, 47, 67, 67) mounted between the first external terminal (33, 43, 53, 63) and the first internal terminal (38,48; 58,68), an inductor (30,40; 50,60) mounted between said first external terminal and the second external terminal (39,49; 59,69) having a capacitance (35,45; 55,65) between said second external terminal and the ground, an inductance (31,41; 51,61) between the second external terminal and the second internal terminal (34,44; 54,64) , and an inductance (32,42; 52,62) between said second and said first internal terminals, with a capacitance (36,46; 56,66) between said second internal terminal and the mass.   4. Device according to claim 3, wherein the ring mixer circuit (17) comprises four field effect transistors (12,13,14,15) each having gate, drain and source electrodes, mounted in a ring with the drains of the adjacent transistors coupled to form the first pair of input terminals (3,4), the sources of the adjacent transistors coupled to form the pair of output terminals (5,6), and the gates of the non-adjacent transistors coupled by two crosswise to provide the second pair of input terminals (1,2), this ring mixer circuit further comprising means for DC biasing (VG, R3; VG, R4) gate-drain of the transistors. An apparatus according to claim 4, comprising a third coupler (20) having an external called terminal (7) for said input signal (ILo) at the frequency of the local oscillator, and a pair of terminals called internal (1). ', 2') for a third signal and its complement (I (LO), I (LOB)) at the frequency of said local oscillator signal, connected to the second pair of input terminals (1,2) of the ring mixer (17), wherein the impedances on said first and second internal terminals are identical with respect to each other of the mass.   6. Device according to claim 5, wherein the third coupler comprises a differential amplifier stage with field effect transistors which receives on the external terminal (7) the input signal ILO at the frequency (LO) of the local oscillator. , and a symmetrical field effect transistor buffer stage output on the internal terminals (1 ', 2') with identical symmetrical impedances vis-à-vis the mass.   7. Device according to one of claims 1 to 6, in   which the field effect transistors of the mixer (17) are of the type MESFET.   8. Device according to one of claims 1 to 6, in   which the field effect transistors of the mixer (17) are of the type MOSFET.   9. Device according to one of claims 1 to 8, which   is monolithically integrated on a semiconductor or semi-   insulation material of a group III-IV material, for operation in Microwave (MMIC).   Device according to claim 9, for operation with an input signal (IRF) and an output signal (OIF) at close frequencies which are approximately five to fifteen times the   value of the signal frequency (IL0) of the local oscillator.   11. Frequency converter apparatus including a   Device according to one of Claims 1 to 10.   12. Transmitting and / or receiving equipment including a   Device according to one of Claims 1 to 10.